How aircraft should become greener

Hannover/London. Low-cost airline Ryanair recently caused a stir with a campaign against cycling and the Irish Green Party. Under the motto ‘flights, not bikes’, the company’s account on social media platform X criticised the Irish Greens and their transport policies.

The loathing is mutual: Ryanair boss Michael O’Leary has long been an outspoken opponent of climate activists. From their perspective, cheap flights are preventing some people from even considering climate-friendly alternatives. Last year, an activist threw a pie at him in front of the European Commission headquarters in Brussels. But can pies change thinking? The trend is moving in the other direction.

This week at the international aviation show in Farnborough, England, the industry once again showed where the journey is headed: more flights, more planes, more passengers. American aircraft manufacturer Boeing published the results of a multi-year forecast ahead of the show. According to this study, almost 44,000 planes would be needed in the entire sector over the next twenty years. Overall, the number of passenger and cargo planes in use worldwide will almost double by 2043, according to the American company.

Aircraft fleets are older than before the pandemic

Travel has become even more important to people than before the pandemic, Boeing manager Darren Hulst explained. Demand is also increasing because machines are being replaced later than usual due to supply bottlenecks. On average, the fleet is about a year to a year and a half older than before the pandemic.

The world’s largest aircraft manufacturer, Airbus, also sees in its own forecast a need for more than 42,000 new aircraft by 2043. However, the company responds: the new aircraft would also replace older models with higher fuel consumption. New technology must at least somewhat combat climate pollution.

Airplanes have become an indispensable means of transportation in modern society.

“Global air traffic doubles approximately every 15 years,” explains Markus Fischer, head of aviation at the German Aerospace Center (DLR). “Airplanes have become an indispensable means of transportation in modern society,” says Fischer. If anyone wants to doubt this, they have to question the entire social development. “Then we would have to do away with many things.”

But how can growth in the aviation industry be reconciled with the need for greater climate protection? The International Civil Aviation Organization (ICAO) predicts that global air traffic will triple by 2050. Without technological improvements, this would also mean a tripling of emissions.

Flying is so harmful to the climate

From the perspective of the Federal Environment Agency, flying is already the most climate-damaging way to travel. “A flight from Germany to the Maldives and back causes a climate impact of around three tonnes of CO₂ equivalents per person,” the agency calculates on its website. For comparison: with a mid-range car you would have to drive more than 15,000 kilometres before the greenhouse gas effect of such a flight would be reached.

Depending on the study, aviation contributes between 3.5 and 5 percent to human-caused global warming. Stopping flying could, in turn, do much to stop climate change. But this seems illusory given the global interconnectedness of humanity and transportation routes. That’s why scientists around the world are focusing on another solution: making flying significantly less harmful to the climate.

DLR has long been working on minimizing the impact of flying. “We want to make aviation so climate-friendly by the middle of the century that we can achieve the goals of the UN Paris Climate Agreement purely through aviation,” says aviation expert Fischer. In a first step, the aircraft’s own energy consumption must be reduced by 50 percent. “If you use less of your own energy, you also need less fuel,” Fischer explains. “That’s the most important step.”

Researchers rely on hybrid technology

There are many approaches: the flow of the aircraft can be optimized, it can be made even lighter and also consume less energy on board. “The transition from incandescent to halogen to LED was a huge leap in this respect,” says Fischer.

The drive is another part of the efforts to reduce emissions. In addition to optimizing the engines, there are also completely new variants – such as an electric drive. From the DLR’s point of view, this makes sense for small aircraft, where it has already been approved for some examples. For larger machines, the researchers rely on hybrid technology – comparable to cars. “This combination has a very, very high potential for aircraft sizes in the regional aircraft sector, i.e. with up to 90 passengers,” emphasizes Fischer. “That goes relatively quickly.” This combination is being investigated in many variants, including in combination with hydrogen drives. Sustainable Aviation Fuel (SAF) also offers a promising perspective for medium to long-haul routes.

But it’s not just technology that can help aircraft reduce emissions. Fischer also sees “huge potential” when it comes to route planning: “There are opportunities to fly a little lower, a little slower, to avoid those areas where aviation emissions are known to have a big impact on the atmosphere.” Because a machine can stay in the air longer, it can potentially save on ground handling. “That’s on the order of five, ten or twenty minutes on long-haul flights.”

At DLR, we see good opportunities to further reduce the climate impact of flying: “In recent decades, we have reduced fuel consumption per seat per 100 kilometers to around a third of what it was in the 1970s,” explains DLR expert Fischer. “And it will go down even further.”